Stripping cathode



W. SYMMES STRIPPING CATHODE Filed Aug. 25. 1947 Sept. 4, 1951 Fig.'

INVENTOR.

atentecl Sept. 4, 1951 UNITED STATES. PATENT OFFICE.

STRIPPING CATHODE Whitman Symmes, Kellogg, Idaho Application August 25, 1947, Serial No. 770,502

3 Claims.

The object of my invention is to provide a stripping cathode from which the deposited sheet of metal may be stripped by mechanical means. The present practice in electrolytic zinc reiineries is to separate the deposited sheet of metal by means of a chisel in the hand of an operator who drives it between an edge of the ldeposited sheet of metal and the permanent cathode plate. This often requires several blows of the chisel.

Advantages of my invention are that the edge of the deposited sheet of metal can be separated from the permanent cathode plate for a definite distance, without fail, and without injury to the cathode plate or the insulating member which I employ thereon. Under these conditions the cathode can be stripped in a suitable m-achine, instead of by hand.

Figure 1 is a view in side elevation of an unplated cathode embodying my invention;

Figure 2 is a view in side elevation of a slightly different form of unplated cathode;

Figure 3 is an enlarged View in side elevation of the insulating member employed in the cathode shown in Figure 1;

Figure a is a section-al view taken on the line 4-4 of Figure 3, showing the insulating member attached to the cathode and the metal plated on the cathode;

Figure 5 is a View like Figure 4, showing the metal being pushed away from the cathode;

Figure 6 is a view, on an enlarged scale, of the upper right corner of the cathode and insulating member of Figure 2; i

Figure 7 is a section view on the line 'l-'l of Figure 6; and

Figure 8 is a fragmentary sectional View on the line 8 8 of Figure 6.

In the illustrations the same numbers indicate the same parts throughout. Figure 1 is a side elevation of an unplated cathode which has insulating members and passageways within the periphery of the cathode plate. The cathode bar l is integral with the cathode plate 2, and the surface of the electrolyte in which it is immersed is indicated by the broken line A-B. An insulating member on the front side is shown at 3, and a passageway through the cathode is shown at 4. Another passageway through the cathode is shown at 5, and a similar insulating member on the opposite side of the cathode plate is indicated by broken lines at 6.

Figure 2 shows another form of an unplated cathode which has insulating members and passageways at the outer edges of the cathode plate. The cathode bar l is integral with the cathode plate 8, which has on its front side an insulating member 9. The cathode plate 8 has an indentation l0 which serves as a passageway connecting the opposite sides of the cathode by means of the space around its edge. A similar insulating member on the opposite side ofthe cathode plate is indicated by broken lines at Il, adjoining the indentation I2. The level of the electrolyte is indicated by the broken line C-D.

Figure 3 shows, on a larger scale, the construction of the insulating member 3. The passageway through the cathode is shown at 4, and I 3 and I4 are bolts above the surface of the electrolyte A-B, for securing the insulating member to the cathode plate.

Figure 4 illustrates the appearance of a cathode along the broken line 4-4 shown in Figure 3, after the permanent cathode plate 2 has had a sheet of metal ldeposited on it in the electrolyte. Note that the cathode plate 2 is bevelled at the passageway 4 and that the insulating material of the member 3 is extended substantially through the passageway so that the metal deposit cannot enter the passageway.

Figure 5 illustrates the manner in which the deposited sheet of metal is separated from the permanent cathode plate at the beginning of the stripping operation.v Thetool employed to press o the depositedsheet of metal is indicated in outline at I6. Y Y

Figure 6 is an enlarged elevationY of insulating member 9 shown in Figure 2.V Bolts attaching it to the permanent cathode plate `are shown at Il and I8. An extension of the cathode plate 8 beyond the insulating member 9 is shown in this iigure. In present practice, in some plants, the cathode plates are dropped into wooden slits that are inserted inside the tanks containing the electrolyte solution and their edges are thereby protected against depositions of metal, In such cases it is necessary to setl the insulating member 9 a suicient distance back from the edge of the cathode so that it will not strike the wooden strips. Figure 6 differs from Figure 2 in this respect. In some plants the cathode plates hang freely in the electrolyte solution. In such cases it is not necessary to set the insulating member back.

Figure 8 illustrates the manner of removing the deposited sheet of metal I9, by a tool which is shown in outline at 2li.

The insulating member may be made of glass, porcelain, plastic or other suitable material, its contacting edges being made to exactly t the cathode plate. The thickness of the metal of i self out from 3 the cathode plate may be reduced from either side by a beveled or curved surface. In Figures 4 and 5 the edge 2l of the cathode plate is bevelled and the insulating member 3 has a lip 22 that overlaps and covers the bevelled edge 2| so that the deposited metal is prevented from attaching itself to the bevelled edge of the cathode. In Figure 8 the cathode face opposite the insulating member 9 is curved at 23to meet the outer edge ofthe member 9, thus,keeping the metal deposit from building up on anv edge of the cathode. In both forms (Fig. and Fig. 8) the exterior angle between the adjacent deposit surface and insulating surface exceeds 180 degreesandin fact closely approaches 270. A thinorsloping edge of the plate should be employed at its contact with the insulation, in order that-,a minimum of pressure may be employed to separate vthe deposited sheet of metal. The insulating member maybe used as a guide to spot the instrument that is-employed to separate the deposited "sheet of-fmetal. The-insulating member may beV attached to the cathode plate-by rubber cement, and-further secured by 'bolts as illustrated. In

the electrolyte thevdeposited metal will buildl itthe edge ofthe conducting .surface into the-passageway sufliciently so that the sheet of-deposited metal may be loosened. by. pressure against it from theopposite side. In zincpractice a onehalf inch roundpassagewaythrough the cathode plate Vwill be restricted to-about `three-eighths inch diameter; or if there is a one in ch-passageway around-the periphery of the cathode, the extension of :deposited metal into the passageway will be aboutone`.-eighth inch. This deposit of metal into the passagewayy takes V'place in the formuof knobs and trees, which firm- -ly unite toeach other and to-the main deposited sheet rof metal. -A light pressure isfsucient to break the vacuum betweentheddeposited metal and thecathode plate at the edgeof the passageway, after-*which the separation is easily followed up. `The-two sheets of metal deposited on lathe opposite sides of the cathode can be stripped simultaneously. `l`4Figures 3,4,and 5 show' the preferred form.

I-claim:

l1. A strippingcathqde plate having an exposed conductive 'surfacev onV one of 4the two Hsides thereof where metal is to be electrolytically deposited, saidplate-having an aperture therein,the edge ,"faceofy the plate deflningithe aperture being Vtapered from the conductive surface toward the ering a portion of the other side of said plate,

said insulating member having an exposed edge face .extending transversely to the plane of said ,plate and lmeeting thesaid exposed conductive deposit surface at an angle greater than dgrees, so that stripping force applied parallel to the edge face of said insulating member against deposited metal overhanging said edge face is directed away from said deposit surface.

3. A strippingcathode plate having an exposed conductivedepositv surface on one of two sides thereof where'metal-is to be-electrolytically deposited, ahard durable insulating member -lcovering a portionof the other side of said plate, said insulating member having an exposed edge-face extending transversely'to the plane of said plate and meeting the said exposed conductive deposit surface at an angle greater` than 180 degrees, so that strippingy force applied parallel to the edge face of said insulating member againstdeposited metal overhanging said edge face is directed away from said deposit-surfacathe saidV platebeing bevelled to reduce the thicknessthereof adjacent said exposed edge face. Y

WHITMAN 4SYMMES` REFERENGES CITED LThe following referencesv areV of record inwthe file of this patent:

.UNITED `STATES PATENTS Number Name Date v 360,672 `Fertig Apr. 5, 1,887 526,482 Bridgman ;Septp2`5, 1894 7,424,862 YHenry A Apr. 7, 1,903

1,468,838 Schuh Sept, 25, 1923 1,507,616 McCarroll ,Sept.'9, 1,924

V2,011,885 Young Aug. 20,1937

,FOREIGN PATENTS Number Country vDate 494,193 Germany Mar;28, 1930 

